1. Field of the Invention
The present invention relates generally to the field of corneal implants and more specifically, to a process for replacing corneal refractive tissue.
2. Prior Art
Blindness and severe vision impairment are often caused by corneal defects. Such defects may for example, result from disease such a bullous keratophy or severe corneal damage such as from accidental intrusion of the eye by a foreign object. In addition, the cornea is sometimes the focus of treatment for the correction of vision defects such as myopia, hyperopia and presbyopia such as by radial keratotomy and keratomeleusus. Radial keratotomy involves a process in which preselected incisions of a precalculated depth, direction and number are made in the cornea to reduce corneal curvature for correction of both myopia and astigmatism. Keratomeleusus involves the carving of frozen cut corneal tissue with a cryolathe. An additional cornea treatment for correcting ophthalmic defects is a process known as epikeratophakia in which precarved and lyophilized corneal tissue is rehydrated and sewn back onto the cornea.
The conventional use of corneal transplants for correcting eye defects suffers from a number of disadvantages. By way of example, there is a shortage of supply of living tissue corneal implants since the corneal tissue is obtained from recently deceased individuals. Most states have legislation which requires permission from the donor prior to his death or from the next of kin of the deceased to make such donated corneal tissue available. In addition, even if the tissue is available in adequate quantities, there is a severe risk of contamination of the tissue during handling and transport. Furthermore, in the event that the donor tissue was diseased, such diseases may be transmitted from the donor to the recipient. Furthermore, there is still a need to freeze the donor tissue in order to cut and shape it to suit the recipient's needs. Finally, there is always the question of ethics of handling tissues of the deceased.
Radial keratotomy is a process which is only suitable for correcting relatively mild cases of myopia and astigmatism. More severe cases of these two afflictions as well as all cases of presbyopia, cannot usually be corrected with radial keratotomy. Keratomeleusus and eipkeratophakia both involve a substantial degree of risk in the handling of a patient's own corneal tissue and reshaping that tissue.
The present invention is designed to reduce or entirely overcome the aforementioned disadvantages of the prior art by providing a process for generating and implanting synthesized corneal-like stromal tissue by the solidification of collagens or collagen-like materials derived from gelatin or other sources.